Speed-limiting device for turbo-generators.



F. R. O, BOYD.

SPEED LIMITING DEVICE FOR TURBO GENERATORS,

APPLICATION FILED SEPT. 2, 1908.

1,090,016. 'Patented Mar. 10, 1914a Fig.1.

i d//6// I Wmne sses: Ir'NerTlbQrj M Frederic RCLESoyd,

UNITED STATES PATENT FREDERIC R. C. BOYD, OF LYNNQMASSACHUSETTS, ASSIGNOR T GENERAL ELECTRIC COMPANY, A CORPORATION 03 NEN YORK.

SPEED-LIMIIJQNG DEVICE FOR TURBO-GENERATORS.

To all whom if m (1 1 comer/1: I 7

Be it known that l, Fiuaomuo R. C. Born,

a citizen of the United States, residing at Lynn, county of Essex, State of Massachuing, is a specification.

This invention relates to turbo-generators, that is to say, dynamo-electric machines driven-by turbine engines, both generator I and turbine having a common shaft.

The idea of means involved in this inveution' is that of pro 'iding an artificialload 'the generator load is lessened, in order to which can be thrown upon the turbine when maintain the turbine load at or near 9. normal amount and'prevent the turbine from exceeding a predetermined speed. I accomplish this by causing the turbine to drive a fan whose blades remain in a position ofminimum action until a predeterminecl'critical'speed is exceeded, when they quickly move to a. position of maximum acsaid blades.

tion,'and eXert a powerful drag upon the turbine shaft, because they have changed v their effective radius and curvature, and increased the width of the passages between I prefer'to attach to the revolving element of the machine a plurality of blades pivotally mounted atone end near the shaft their other ends being free to outwardly under the influence of centrifugal; force in accordanceugith any accelerat on 111 speed of said shaft above a critical point. In their inmost position the free ends of the blades lie close'to fixed portions of the revolving member, suchfor example as the studs upon which said blades are mounted. There is then no outlet for the fair between the blades, and any pressure due to the confined air is resisted by the blades, which are made preferably of resilient material, such as flexible spring-tempered steel. They are assembled with a certain amount of initial tcnsion tending to hold them closed upon one another during low speeds. But as, soon as the speed exceeds a predetermined number of revolutions per minute, the centrifugal force of these bladesequals the, initial tension, with the result that they startdeflectin'g outwardly. By properly proportioning the spring-blades they Will travel to the limit of their outward movement with only Specification of Letters Patent.

Appfieation filed September 2, 1908.

tion and vice versa, within small changes Patented Mar. 3U); fte iet. Serial No. 451,313.

a slight increase of speed on the part or the machine. This outward travel. causes the blades to exert a decided retardation on the rotating element to which they are attached, so that its excess of speed is limited. Upon returning to normal speed, thc springr bl; aga n resume their losely folded posit Their action is thus one of rapid cha' trom a minimum to a maximum of ret in speed of the machine, instead of t g edual change during a considerable alteration in speed.

In the accompanying drawingjFigure 1 is a longitudinal sectional elevation ofa tur lune driving: a generator and equipped with my speed limiting device. and Fig. 53 is a 'crosssection on the line 2 -2, l, on a larger scale.

The shaft- 1' is common to the s enerator 7 and the turbine 3, one of whose bucket-- wheels is shown at 4. The direction of rotation is clockwise in 9! A dish 5 is mounted on the shaft and carries a phi-- rality of studs 6 projecting therefrom like WIlSiJ PlDS, and spaced equi-distant. each stud is secured one end of a fiat steel spring blade 7, its other and resting normally on the adjoining stud in tho rear. The spring blade is given a predetermined initial tension and may be slightly curved, to keep it close to the axis of rotation at all speeds up to apredetermined maximum. Any slight increase above-tho critical speed causes the centrifugal force of the blade to throw it outwardly until arrested by suit able means such as a stop 8. The blac e also tends to reverse its curmture, so that its tip is swung out still further from the shaft as shown by the dotted lines in Fig. 2. in this position the blades exert a powerful damp 'iug action on the shaft, slowing it quickly to normal speed, lhe additional loalthrown on the turbine when the blades y outward is due to at least three causes; first, the increased fan action due to the higher speed; second, the increased fan action due to the greater radius of the blades, and third, the increased. fan action due to the increased Width of the air passages which allows a greater volume of air to be piunped and. to the change in the curvature of the blades which causes a greater amount of power to be absorbed in driving them.

The fan may be utilized to cool the gener-- ator by drawing the air in through a port 9 at one end of the casing 10 inclosing said generator, and admitting it to the fan through an annular opening 11 in theend of said casing concentricwith the shaft. The fan may be inclosed by a wall 12 having an opening in which the disk 5 is rotatably fitted. Ribs 13 radial to the fan connect said wall with the end of the generator casing and serve to direct the air currents outwardly away from the fan. The air can escape through a hole 14- in the easmg.

In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention together with the apparatus which I now consider to represent the best embodiment thereof; but I desire to have it understood that the apparatus shown is only illustrative, and that the invention can be carried out by other means.

What I claim as new and desire to secure v by Letters Patent of the United States, is,

1. A speed. limiting device for a prime mover comprising a fan having a plurality of tangentially arranged resilient blades, and means defining a passage for the admission of air to the blades, said blades delivering the air from between the same to the periphery thereof and being capable of swinging outward under centrifugal force when a certain predetermined speed is reached, whereby the same present an increased radius and a greater vane space.

'2. A speed limiting device for a prime mover comprising a fan having a plurality of tangentially arranged resilient blades, means defining a passage for the admission of air to the blades, said blades delivering the air from between the same to the periph ery thereof and being capable of swinging outward under centrifugal force when a certain predetermined speed is reached whereby the same present an increased radius and a greater vane space, and means for causing the blades to reverse their curvature as they move outward.

3. A speed limiting device for a prime mover comprising a fan having a plurality of tangentially arranged resilient blades normally curved away from the direction of rotation, means defini'ngan annular passage for the admission of air to the blades,

' said blades delivering the air from between the same to the periphery thereof and being capable of swinging outward under centrifugal force when a certain predetermined speed is reached, whereby the same present an increased radius and a greater vane space, and means for causing the blades to reverse their curvature so they present their curved surfaces toward the direction of rotation as they move outward.

a. A speed limiting device for a prime mover comprising a fan having a plurality of tangentially arranged resilient blades fixed at one end and having their 'lree ends normally under tension tending to hold them closed upon one another, means defining a passage for the admission of air to the blades, said blades delivering the air to the periphery thereof and-being capable of swinging outward under centrifugal force when a certain predetermined speed is exceeded whereby the same present an increased radius and a greater vancspace.

5. The combination in a speed limiting device for a prime mover, of a plurality of resilient fan blades fixed at one end and arranged around the shaft of the prime mover, said blades being under an initial tension tending to hold them close to the shaft, and

FREDERIC R. C. BOYD.

-lll itnesse s ALEX. F. MACDONALD, LEWIS SANDERS. 

